Saturation boiling of HFE-7100 from a copper surface, simulating a microelectronic chip

Experiments are performed, which investigated the effect of inclination angle, (theta), on saturation pool boiling of HFE-7100 dielectric liquid from a smooth, 10*10 mm copper surface, simulating a microelectronic chip. For (theta)<=90(degree) and surface superheats, (delta)Tsat>20 K, nucleate boiling heat flux decreases with increased (theta), but increases with (theta)for (delta)Tsat<20 K. Similarly, at higher inclinations and (delta)Tsat>13 K, nucleate boiling heat flux decreases with increased inclination, but at lower surface superheats the trend is inconclusive. The developed nucleate boiling correlation is within +-10% of the data and the developed correlations for critical heat flux (CHF) and the surface superheat at CHF are within +-3% and +-8% of the data, respectively. Results show that CHF decreases slowly from 24.45 W/cm2 at 0(degree) to 21 W/cm^2 at 90(degree), then decreases fast with increased (theta)to 4.30 W/cm2 at 180(degree). The surface superheat at CHF also decreases with (theta), from 31.7 K at 0(degree) to 19.9 K at 180(degree). Still photographs are recorded of pool boiling at different heat fluxes and (theta)=0(degree), 30(degree), 60(degree), 90, 120(degree), 150(degree) and 180(degree). The measured average departure bubble diameter from the photographs taken at the lowest nucleate boiling heat flux of ~0.5 W/cm^2 and (theta)=0(degree) is 0.55+-0.07 mm and the calculated departure frequency is ~100 Hz.